This invention relates to a multi contact connector having a ground terminal block connected with tape wires and a method of connecting tape wires to a mult contact connector having a ground terminal block.
In electronic instruments such as electronic computers, connectors have been widely used, for example, for connecting printed circuit boards constituting devices to each other and connecting printed circuit boards and external devices.
In this case, for example, as shown in FIG. 1 which is a perspective view illustrating a typical connector of prior art, a printed circuit board 1 is connected to an external circuit by inserting into a receptacle connector 2 connected and fixed to the printed circuit board 1 a plug connector 5 having a ground terminal block 4 and signal and power source terminals 3 respectively corresponding to ground terminals and signal and power source terminals of the board 1. The plug connector 5 is connected through wires to the external circuit. In this case, instead of conventional single wires, flexible tape wires 6 are often used which comprise bare wires 7 corresponding in number and interval to contacts of the connector and coated by an insulator 8 in the form of a tape as shown in FIG. 1.
On the other hand, in connecting the bare wires of the tape-like wires to the signal and power source terminals of the plug connector, the bare wires 7.sub.1 and 7.sub.2 which have been cut so as to be positioned on the signal and power source terminals 3 and the ground terminal block 4, respectively, are embraced between welding electrodes to weld these bare wires to the terminals 3 and the block 4 while the wires abut thereagainst as shown in FIG. 1.
Recently, electronic parts have been miniaturized to increase the number of parts on printed circuit boards. The increase of the number of parts requires the miniaturization of connectors and an increase in the number of contacts of the connectors. As the result, width of connecting terminals of connectors and intervals of the terminals have been narrowed limitlessly and diameters of bare wires have become thinner limitlessly. Therefore, as the connectors have been miniaturized and greatly increased their contacts, there is a risk of welding strength being lowered to allow the wires to be disconnected relatively easily by external tensile forces acting upon the tape wires. Moreover, as the diameters of the bare wires have become thinner, the mechanical strength of the bare wires themselves resisting the external tensile forces has decreased. Accordingly, in the event that the partial bare wires are concentrically subjected to external forces, there is a risk of disconnection of the partial bare wires between the insulatingly coated portions and the welded terminals, even if the bare wires in the insulating coating subjected to distributed tensile forces do not disconnect. This risk is relatively slight in the bare wires 7.sub.2 connected to the ground terminal block 4 but particularly acute in the bare wires 7.sub.1 connected to the signal and power source terminals and extending from the coated portions to the welded portions. In other words, there is a tendency of the signal and power source wires to be easily disconnected, which are important because disconnection of only one wire causes an obstruction of the operation of the device. On the other hand, the bare wires for the ground terminals are more difficult to disconnect in comparison with the signal and power source wires, in spite that any obstruction of the operation of the device is not caused, even if a few strands for the ground terminals are disconnected.